"While there is clearly sensitivity about it, I think experience shows one needs to be very public about these problems in some of these countries," she said.

"We need to add our voice to what's coming out of the US, Europe and many Asian countries themselves who are deeply troubled about Mr Somphone's safety."

The first assistant secretary of Australia's Foreign Affairs Department, Rod Smith, has told a Senate Estimates hearing Mr Sombath worked with Australia on human rights programs in Laos.

"We've registered with the Lao Government our expectation that they will properly investigate his disappearance and the circumstances of his disappearance and they do what they can to locate him," Mr Smith said.

Sombath Somphone, 60, received the Ramon Magsaysay Award for community leadership in 2005 and worked to promote education and development in poverty-stricken Laos.

The Lao Ministry of Foreign Affairs says traffic police had stopped Mr Sombath in the course of routine checks on December 15.

CCTV video footage, obtained by Mr Sombath's family and published online, show him being taken away from a police post by two unidentified men and has not been seen since.

A statement from the Lao authorities says that "it may be possible Mr Sombath has been kidnapped."

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